Terminals, base stations, and communication methods

Abstract

To reduce power consumption related to wireless communication at NTN. [Solution] The terminal according to the embodiment of this disclosure comprises a control unit and a transmitting unit. The control unit selects a first cell of a first base station that provides wireless communication via a geostationary satellite and a second cell of a second base station that provides wireless communication via an aircraft that is closer to the ground than a geostationary satellite. The transmitting unit transmits a message relating to a registration request to the second cell.

Description

[Technical Field]

[0001] The present disclosure relates to a terminal, a base station, and a communication method. [Background Art]

[0002] 3GPP (3rd Generation Partnership Project) (registered trademark) has standardized NR (New Radio) (also referred to as "5G"), which is a successor system to LTE (Long Term Evolution) (registered trademark). Furthermore, 3GPP is proceeding with the standardization of 5G-Advanced and 6G as next-generation systems.

[0003] Currently, NTN (Non-Terrestrial Network) is being studied in the standardization of 5G-Advanced and 6G. NTN provides services to areas that cannot be covered mainly in terms of cost by terrestrial 5G networks, for example, by using non-terrestrial networks such as artificial satellites. [Prior Art Documents] [Non-Patent Literature]

[0004] [Non-Patent Literature 1] 3GPP TS 38.300 V18.4.0 Release 18, “5G; NR; NR and NG-RAN Overall description; Stage-2”, 2025. [Non-Patent Literature 2] 3GPP TR 38.821 V16.2.0 Release 16, “Solutions for NR to support non-terrestrial networks (NTN)”, 2023. [Non-Patent Literature 3] 3GPP TR 22.887 V1.0.0 Release 20, “Study on satellite access - Phase 4”, 2024. [Overview of the project] [Problems that the invention aims to solve]

[0005] At NTN, terminals may communicate wirelessly via geostationary satellites. In such cases, terminals communicate over longer distances than they would with base stations in conventional terrestrial 5G networks. Long-distance wireless communication may increase the transmission power of the terminal.

[0006] One of the purposes of this disclosure is to reduce power consumption related to wireless communication at NTN. [Means for solving the problem]

[0007] A terminal according to the embodiment of this disclosure comprises a control unit and a transmitting unit. The control unit selects a first cell of a first base station that provides wireless communication via a geostationary satellite and a second cell of a second base station that provides wireless communication via an aircraft closer to the ground than a geostationary satellite. The transmitting unit transmits a message relating to a registration request to the second cell. [Effects of the Invention]

[0008] This disclosure can reduce power consumption related to wireless communication at NTN. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of an NTN according to the embodiment. [Figure 2] This block diagram shows an example of the configuration of a wireless communication system according to the embodiment. [Figure 3] This figure shows a specific example of NTN according to the embodiment. [Figure 4] This is a sequence diagram showing an example of the registration procedure according to the embodiment. [Figure 5] This is a sequence diagram showing a first example of the AN release procedure and paging message reception flow according to the embodiment. [Figure 6] This sequence diagram shows a second example of the AN release procedure and paging message reception flow according to the embodiment. [Figure 7] This is a sequence diagram showing an example of the service request procedure according to the embodiment. [Figure 8] This is a block diagram showing an example of the functional configuration of a base station according to the embodiment. [Figure 9] This block diagram shows an example of the functional configuration of a terminal according to the embodiment. [Figure 10] A block diagram showing an example of the hardware configuration of a base station or terminal according to the embodiment. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described below with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which this disclosure applies are not limited to those described below.

[0011] Existing technologies will be used as appropriate in the operation of the wireless communication system of the embodiment. However, such existing technologies include, for example, existing LTE, but are not limited to existing LTE. Furthermore, the term "LTE" as used herein has a broad meaning that includes LTE-Advanced and LTE-Advanced and later methods (e.g., NR), unless otherwise specified.

[0012] Furthermore, in the embodiments described below, terms such as SS (Synchronization signal), PSS (Primary SS), SSS (Secondary SS), PBCH (Physical broadcast channel), PRACH (Physical random access channel), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), PUCCH (Physical Uplink Control Channel), and PUSCH (Physical Uplink Shared Channel), which are used in existing LTE systems, will be used. This is for convenience of description, and similar signals, functions, etc., may be called by other names. Also, the above terms in NR correspond to NR-SS, NR-PSS, NR-SSS, NR-PBCH, NR-PRACH, NR-PDCCH, NR-PDSCH, NR-PUCCH, NR-PUSCH, etc. However, even if a signal is used in NR, it is not necessarily explicitly stated as "NR-".

[0013] (assignment) To date, use cases and solutions for wireless communication with geostationary satellites have been considered. Similarly, use cases and solutions for wireless communication with low Earth orbit satellites have also been explored. However, at present, optimized solutions, particularly regarding the reduction of power consumption for wireless communication, have not been discussed for use cases involving multiple satellites in multiple orbits. Solutions for efficiently utilizing multiple satellites need to be considered.

[0014] (Embodiment) NTN (Non-Terrestrial Network) provides services to areas that cannot be covered mainly in terms of cost by terrestrial 5G networks, using non-terrestrial devices such as satellites. Further, NTN can provide services with higher reliability than networks configured only with terrestrial 5G networks. For example, NTN is expected to be applied to communications in IoT (Internet of Things), ships, buses, trains and the like, emergency communications, and other important communications. NTN also has scalability through efficient multicast or broadcast.

[0015] Note that a terrestrial 5G network may have a configuration as described below. A terrestrial 5G network includes one or more base stations and one or more terminals. A base station is a communication device that provides one or more cells and performs wireless communication with terminals. Physical resources of a wireless signal are defined in the time domain and the frequency domain. The time domain may be defined by the number of OFDM symbols, and the frequency domain may be defined by the number of subcarriers or the number of resource blocks. A base station transmits a synchronization signal and system information to a terminal. The synchronization signal is, for example, NR-PSS and NR-SSS. The system information is transmitted, for example, via NR-PBCH, and is also referred to as broadcast information. The synchronization signal and the system information may also be referred to as an SS / PBCH block.

[0016] A base station transmits control signals or data to a terminal via DL (Downlink), and receives control signals or data from the terminal via UL (Uplink). Both the base station and the terminal can perform beamforming to transmit and receive signals. Further, both the base station and the terminal can apply MIMO (Multiple Input Multiple Output) communication to DL or UL. Further, both the base station and the terminal may perform communication via SCell (Secondary Cell) and PCell (Primary Cell) based on CA (Carrier Aggregation).

[0017] The terminal is a communication device equipped with wireless communication capabilities, such as a smartphone, mobile phone, tablet, wearable device, and M2M (Machine-to-Machine) communication module. The terminal receives control signals or data from the base station via DL and transmits control signals or data to the base station via UL, thereby utilizing various communication services provided by the wireless communication system.

[0018] Figure 1 shows an example of an NTN according to an embodiment. As shown in Figure 1, the NTN may be realized via an aircraft 10A in space or in the air. The aircraft 10A may include, for example, an artificial satellite (hereinafter sometimes simply referred to as "satellite"), a HAPS (High Altitude Platform Station), an aircraft, and a drone. Artificial satellites include, for example, geostationary orbit satellites (GEO satellites) that orbit geostationary orbit (GEO) and low Earth orbit satellites (LEO satellites) that orbit low Earth orbit (LEO). Low Earth orbit satellites are closer to the ground than geostationary orbit satellites. The HAPS may be, for example, an unmanned aerial vehicle that orbits in the stratosphere.

[0019] As shown in Figure 1, the aircraft 10A may access the base station 10C via the ground station 10B. This allows the service area of ​​the base station 10C to extend to the range within which it can communicate with the antenna mounted on the aircraft 10A. In Figure 1, service area SA1 corresponds to GEO satellites, service area SA2 corresponds to LEO satellites, and service area SA3 corresponds to HAPS. For example, the service areas may increase in the order of HAPS, LEO satellites, and GEO satellites. The radio link between the aircraft 10A and the ground station 10B is called a feeder link. The radio link between the aircraft 10A and the terminal 20 is called a service link.

[0020] For example, NTN can extend 5G network coverage to both areas where the 5G network is not yet serviced and areas where it is already serviced. Furthermore, NTN can improve the continuity, availability, and reliability of services in IoT, ships, buses, and trains, as well as in emergency and other critical communications. The fact that it is NTN may be indicated by the transmission of a special parameter to terminal 20. This special parameter may, for example, be a parameter related to the determination of Timing Advance (TA) based on information relating to the aircraft 10A.

[0021] Figure 2 is a block diagram showing an example of the configuration of a wireless communication system according to the embodiment. The wireless communication system in Figure 2 comprises a RAN 10, a terminal 20, a core network 30, and a DN (Data Network) 40.

[0022] RAN10 comprises a ground station 10B and a base station 10C. Ground station 10B relays communication between base station 10C and terminal 20 or aircraft 10A. Base station 10C may also be called gNB (gNodeB).

[0023] The core network 30 is a network equipped with exchanges, subscriber information management devices, etc. The core network 30 comprises network nodes that implement U-Plane functionality and a group of network nodes that implement C-Plane functionality.

[0024] The U-Plane function is a function that performs the processing of sending and receiving user data. A network node that implements the U-Plane function is, for example, the UPF (User plane function) 380. The UPF 380 is a network node that has functions such as an external PDU (Protocol Data Unit) session point for mutual access with the DN 40, packet routing and forwarding, and user plane QoS (Quality of Service) handling. The UPF 380 controls the sending and receiving of data between the DN 40 and the terminal 20. The UPF 380 and DN 40 may consist of one or more network slices.

[0025] The C-Plane function group is a set of functions that execute a series of control processes for establishing communication and other purposes. The network node group that implements the C-Plane function group includes, for example, AMF (Access and Mobility Management Function) 310, UDM (Unified Data Management) 320, NEF (Network Exposure Function) 330, NRF (Network Repository Function) 340, AUSF (Authentication Server Function) 350, PCF (Policy Control Function) 360, SMF (Session Management Function) 370, and AF (Application Function) 390.

[0026] The AMF310 is a network node with functions such as RAN interface termination, NAS (Non-Access Stratum) termination, registration management, connection management, reachability management, and mobility management. The AMF310 also includes SEAF (SEcurity Anchor Function), which acts as a security anchor in the serving network.

[0027] NRF340 is a network node with the ability to discover NF (Network Function) instances that provide services. UDM320 is a network node that manages subscriber data and authentication data. UDM320 includes a UDR (User Data Repository)321 that holds the data and a FE (Front End)322. FE322 processes subscriber information. UDM320 may also include an ARPF (Authentication credential Repository and Processing Function). ARPF is a network node that has an authentication credential repository and processing function. AUSF350 is a network node that has an authentication function for terminals.

[0028] The SMF370 is a network node with functions such as session management, IP (Internet Protocol) address assignment and management for terminal 20, DHCP (Dynamic Host Configuration Protocol) functionality, ARP (Address Resolution Protocol) proxy, and roaming functionality. The NEF330 is a network node with the function of notifying other NFs (Network Functions) of their capabilities and events. The PCF360 is a network node with the function of controlling network policies.

[0029] The AF (Application Function) 390 is a network node that has the function of controlling application servers.

[0030] The interface between AMF310 and RAN10 may be called N2 (or N2 interface). The interface between UPF380 and RAN10 may be called N3 (or N3 interface). The interface between UPF380 and SMF370 may be called N4 (or N4 interface). The interface between UPF380 and DN40 may be called N6 (or N6 interface).

[0031] Figure 3 shows a specific example of NTN according to the embodiment. Figure 3 shows a geostationary satellite 10A-1, a first ground station 10B-1, a first base station 10C-1, a low Earth orbit satellite 10A-2, a second ground station 10B-2, a second base station 10C-2, a terminal 20, and a core network 30.

[0032] Geostationary satellite 10A-1 is mutually accessible with the first base station 10C-1 via the first ground station 10B-1. Low Earth orbit satellite 10A-2 is mutually accessible with the second base station 10C-2 via the second ground station 10B-2. The first base station 10C-1 and the second base station 10C-2 are mutually accessible with the core network 30.

[0033] Furthermore, the geostationary satellite 10A-1 covers a first cell C1, which is the range within which communication is possible on the ground. That is, the first cell C1 may also be called the cell of the first base station 10C-1 that provides wireless communication via the geostationary satellite 10A-1. Note that the first cell C1 may, for example, have a fixed position on the ground.

[0034] Furthermore, the low Earth orbit satellite 10A-2 covers a second cell C2, which has a smaller range than the first cell C1. That is, the second cell C2 may also be called the cell of the second base station 10C-2, which provides radio communications via the low Earth orbit satellite 10A-2.

[0035] In the specific example shown in Figure 3, terminal 20 is capable of wireless communication with both geostationary satellite 10A-1 and low Earth orbit satellite 10A-2. In other words, terminal 20 is within the range of the first cell C1 and the second cell C2.

[0036] In the situation shown in Figure 3, terminal 20 selects both the first cell C1 and the second cell C2 by performing a cell search. After selecting both cells, terminal 20 performs a registration procedure with the second base station 10C-2 via the low Earth orbit satellite 10A-2. The registration procedure includes, for example, registering the location of terminal 20. The flow of the registration procedure will be explained below with reference to Figure 4.

[0037] Figure 4 is a sequence diagram showing an example of the registration procedure according to the embodiment. The sequence diagram in Figure 4 shows, for example, the flow of operations after the user turns on the power of terminal 20.

[0038] (Step S101) After the user powers on terminal 20, terminal 20 may perform a cell search. At this time, the connection state between terminal 20 and the second base station 10C-2 may be the RRC idle state (RRC_IDLE) in the Radio Resource Control (RRC) state. The RRC idle state is a state in which an RRC connection has not been established.

[0039] (Step S102) The second base station 10C-2 may transmit SS / PBCH blocks within the range of the second cell C2 at regular intervals via the low Earth orbit satellite 10A-2. The SS / PBCH blocks transmitted from the second base station 10C-2 may include, for example, information from the low Earth orbit satellite 10A-2. By performing a cell search, the terminal 20 may receive SS / PBCH blocks from the second base station 10C-2.

[0040] (Step S103) The first base station 10C-1 may transmit SS / PBCH blocks within the range of the first cell C1 at regular intervals via the geostationary satellite 10A-1. The SS / PBCH blocks transmitted from the first base station 10C-1 may include, for example, information from the geostationary satellite 10A-1. By performing a cell search, the terminal 20 may receive SS / PBCH blocks from the first base station 10C-1.

[0041] (Step S104) After receiving SS / PBCH blocks from the first base station 10C-1 and the second base station 10C-2, respectively, terminal 20 may select the first cell C1 of the first base station 10C-1 and the second cell C2 of the second base station 10C-2. After selecting both cells, terminal 20 may decide to perform a registration procedure with the second base station 10C-2 via the low Earth orbit satellite 10A-2. The random access procedure from terminal 20 to the second base station 10C-2 is omitted from this description.

[0042] (Step S105) After deciding to perform the registration procedure with the second base station 10C-2, terminal 20 may send an RRCSetupRequest message to the second base station 10C-2. The second base station 10C-2 may receive an RRCSetupRequest message from terminal 20.

[0043] (Step S106) After receiving an RRCSetupRequest message, the second base station 10C-2 may send an RRCSetup message to the terminal 20. The terminal 20 may receive an RRCSetup message from the second base station 10C-2.

[0044] (Step S107) After receiving the RRCSetup message, terminal 20 may send an RRCSetupComplete message, including a registration request message, to the second base station 10C-2. The second base station 10C-2 may receive the RRCSetupComplete message from terminal 20.

[0045] After terminal 20 sends the RRCSetupComplete message, the connection status between terminal 20 and the second base station 10C-2 may switch from the RRC idle state (RRC_IDLE) to the RRC connected state (RRC_CONNECTED). Note that the procedures after the registration request are omitted as they can be performed using the previous procedure.

[0046] (Step S108) After the registration procedure at the second base station 10C-2 is completed, the second base station 10C-2 may send a DLInformationTransfer message including a registration acceptance message to terminal 20. Terminal 20 may receive a DLInformationTransfer message from the second base station 10C-2. Upon receiving the DLInformationTransfer message, terminal 20 may configure itself to receive paging messages from the first cell C1 and stop cell discovery for the second cell C2. Alternatively, terminal 20 may send a ULInformationTransfer message including a registration complete message to the second base station 10C-2.

[0047] Furthermore, the source and destination of data in a terminal may be represented in terms of cells. That is, "The terminal receives data from the base station" can be reinterpreted as "The terminal receives data from a cell," and "The terminal sends data to the base station" can be reinterpreted as "The terminal sends data to a cell." These points will continue as well.

[0048] In summary, as shown in the sequence diagram of Figure 4, terminal 20 may select the first cell C1 of the first base station 10C-1, which provides wireless communication via geostationary satellite 10A-1, and the second cell C2 of the second base station 10C-2, which provides wireless communication via low Earth orbit satellite 10A-2, and send a message regarding the registration request to the second cell C2. As a result, terminal 20 can perform the registration procedure via low Earth orbit satellite 10A-2, thereby reducing the transmission power compared to performing the registration procedure via geostationary satellite 10A-1.

[0049] Furthermore, terminal 20 may receive a message from the second cell C2 regarding the acceptance of a registration request. If terminal 20 receives such a message, it may configure itself to receive a paging message from the first cell C1 and stop cell searching for the second cell C2. This allows terminal 20 to reduce power consumption associated with cell searching.

[0050] Note that steps S102 and S103 described above may be performed in any order. That is, terminal 20 may receive an SS / PBCH block from the first base station 10C-1 and then receive an SS / PBCH block from the second base station 10C-2.

[0051] Furthermore, at some point after step S108 described above, terminal 20 may cease cell searches for the low Earth orbit satellite 10A-2. This point in time could be, for example, when terminal 20 is in a state where it is monitoring system information and paging messages in the first cell C1 (this may be called "camping" or "camp-on").

[0052] Next, we will explain the AN release procedure and the flow of receiving paging messages that occur after the registration procedure is completed, using two examples. The first example is one in which, during the AN release procedure, Recommended Cells for Paging and Recommended RAN Nodes for Paging are provided to AMF310 as the first cell C1 and the first base station 10C-1. The second example is one in which, during the AN release procedure, Recommended Cells for Paging and Recommended RAN Nodes for Paging are provided to AMF310 as the second cell C2 and the second base station 10C-2.

[0053] Figure 5 is a sequence diagram showing a first example of the flow of the AN release procedure and paging message reception according to the embodiment. The sequence diagram in Figure 5 shows, for example, the flow of operations after the registration procedure in Figure 4 is completed.

[0054] (Step S201) After the registration procedure is completed, the second base station 10C-2 may send an RRC release message to the terminal 20. After the second base station 10C-2 sends the RRC release message, the connection state between the terminal 20 and the second base station 10C-2 may switch from the RRC connected state to the RRC idle state. In other words, the second base station 10C-2 releases the radio connection and context related to the terminal 20.

[0055] (Step S202) After sending the RRCRelease message to terminal 20, the second base station 10C-2 may send a UE CONTEXT RELEASE REQUEST message to AMF310. AMF310 may receive the UE CONTEXT RELEASE REQUEST message from the second base station 10C-2.

[0056] (Step S203) After receiving the UE CONTEXT RELEASE REQUEST message, AMF310 may send a UE CONTEXT RELEASE COMMAND message to the second base station 10C-2. The second base station 10C-2 may receive the UE CONTEXT RELEASE COMMAND message from AMF310.

[0057] (Step S204) After receiving the UE CONTEXT RELEASE COMMAND message, the second base station 10C-2 may set the first cell C1 and the first base station 10C-1 in the message's information element (IE) based on the local settings. At this time, the second base station 10C-2 may have obtained control data concerning the low Earth orbit satellite 10A-2 (such as satellite operation information (satellite orbit information), including the satellite ephemeris) from NTN's unique OAM (Operations Administration and Maintenance). Therefore, the local settings may contain information about the first cell C1 and the first base station 10C-1 concerning the geostationary satellite 10A-1, which covers the orbital position of the low Earth orbit satellite 10A-2, corresponding to the time. Specifically, the second base station 10C-2 may set the first cell C1 as the recommended paging cell and the first base station 10C-1 as the recommended paging RAN node in the "Information on Recommended Cells and RAN Nodes for Paging" information element of the UE CONTEXT RELEASE COMPLETE message in response to the UE CONTEXT RELEASE COMMAND message. Note that the recommended paging cell and recommended paging node information may each be represented by identifiers.

[0058] (Step S205) After receiving the UE CONTEXT RELEASE COMMAND message, the second base station 10C-2 may send a UE CONTEXT RELEASE COMPLETE message containing the above-mentioned information elements to the AMF310. The AMF310 may receive the UE CONTEXT RELEASE COMPLETE message from the second base station 10C-2. In this case, since the UE CONTEXT RELEASE COMPLETE message contains the above-mentioned information elements, the AMF310 may save the contents of these information elements and use them to send a subsequent Paging message.

[0059] (Step S206) After receiving the UE CONTEXT RELEASE COMPLETE message, AMF310 may send a Paging message to the first base station 10C-1. The first base station 10C-1 may receive the Paging message from AMF310.

[0060] (Step S207) After receiving a Paging message, the first base station 10C-1 may send the Paging message to the first cell C1 where terminal 20 is camped. Terminal 20 may receive a Paging message addressed to itself.

[0061] Figure 6 is a sequence diagram showing a second example of the AN release procedure and paging message reception flow according to the embodiment. The sequence diagram in Figure 5 shows, for example, the flow of operations after the registration procedure in Figure 4 is completed. Note that the processing in steps S301, S302, and S303 is the same as the processing in steps S201, S202, and S203 in Figure 5, so the explanation is omitted.

[0062] (Step S304) After receiving the UE CONTEXT RELEASE COMMAND message, the second base station 10C-2 may send a UE CONTEXT RELEASE COMPLETE message to the AMF310. The information element "Information on Recommended Cells and RAN Nodes for Paging" included in the UE CONTEXT RELEASE COMPLETE message may be set to the second cell C2 as the recommended paging cell and the second base station 10C-2 as the recommended paging RAN node. The AMF310 may receive the UE CONTEXT RELEASE COMPLETE message from the second base station 10C-2. At this time, since the UE CONTEXT RELEASE COMPLETE message contains the above-mentioned information element, the AMF310 may save the contents of this information element and use it to send a subsequent Paging message.

[0063] (Step S305) After receiving the UE CONTEXT RELEASE COMPLETE message, AMF310 may send a Paging message to the second base station 10C-2. The second base station 10C-2 may receive the Paging message from AMF310.

[0064] (Step S306) After receiving a Paging message, the second base station 10C-2 may decide to forward the Paging to the first base station 10C-1 based on its local settings. The local settings may include information about the first cell C1 and the first base station 10C-1 regarding the geostationary satellite 10A-1, which covers the orbital position of the low Earth orbit satellite 10A-2, corresponding to the time.

[0065] (Step S307) The second base station 10C-2 may send a Paging message to the first base station 10C-1. The first base station 10C-1 may receive a Paging message from the second base station 10C-2.

[0066] (Step S308) After receiving a Paging message, the first base station 10C-1 may send a Paging message to the first cell C1 where terminal 20 is camped. Terminal 20 may receive a Paging message addressed to itself.

[0067] Next, we will describe the flow of the service request procedure that takes place after terminal 20 receives a paging message.

[0068] Figure 7 is a sequence diagram showing an example of the service request procedure flow according to the embodiment. The sequence diagram in Figure 7 shows, for example, the flow of operations after terminal 20 receives a paging message in Figure 5 or Figure 6.

[0069] (Step S401) After receiving a Paging message, terminal 20 may send an RRCSetupRequest message to the second base station 10C-2. The second base station 10C-2 may receive an RRCSetupRequest message from terminal 20.

[0070] (Step S402) After receiving an RRCSetupRequest message, the second base station 10C-2 may send an RRCSetup message to the terminal 20. The terminal 20 may receive an RRCSetup message from the second base station 10C-2.

[0071] (Step S403) After receiving the RRCSetup message, terminal 20 may send an RRCSetupComplete message, including a SERVICE REQUEST message, to the second base station 10C-2. The second base station 10C-2 may receive the RRCSetupComplete message from terminal 20.

[0072] After terminal 20 sends the RRCSetupComplete message, the connection status between terminal 20 and the second base station 10C-2 may switch from the RRC idle state (RRC_IDLE) to the RRC connected state (RRC_CONNECTED). Note that the procedures after the service request are omitted as they can be handled using the previous procedure.

[0073] (Step S404) After the service request procedure at the second base station 10C-2 is completed, the second base station 10C-2 may send a DLInformationTransfer message including a SERVICE ACCEPT message to the terminal 20. The terminal 20 may receive a DLInformationTransfer message from the second base station 10C-2.

[0074] In the example shown in Figure 7, terminal 20 performed a service request procedure to the second base station 10C-2, but this is not limited to this. Terminal 20 may also perform a service request procedure to the first base station 10C-1.

[0075] To summarize the sequence diagrams in Figures 5, 6, and 7, terminal 20 may receive a paging message transmitted from the first cell C1 and send a service request message to the second cell C2. As a result, terminal 20 can perform the service request procedure via the low Earth orbit satellite 10A-2, thereby reducing the transmission power compared to performing the service request procedure via the geostationary orbit satellite 10A-1.

[0076] Furthermore, the second base station 10C-2 may manage the radio connection and context related to terminal 20, and when releasing the radio connection and context related to terminal 20, it may send a message to the AMF310 that includes information designating the first base station 10C-1, which provides radio communication via geostationary satellite 10A-1, as the destination for paging messages.

[0077] Alternatively, the second base station 10C-2 may receive a paging message from a network node and transmit the paging message to the first base station 10C-1, which provides wireless communication via the geostationary satellite 10A-1.

[0078] (Other examples of embodiments) In the above embodiment, an example of NTN's architecture in which base stations are located on the ground was described, but it is not limited to this. For example, the functions of a base station may be provided on a satellite (at least one of the geostationary satellite 10A-1 and the low Earth orbit satellite 10A-2), and the core network may be accessed from the satellite base station.

[0079] The low Earth orbit satellite in the above embodiment may be one of the satellites constituting a satellite constellation. If the low Earth orbit satellite in the embodiment constitutes a satellite constellation, information about the terminal received by the low Earth orbit satellite in the embodiment may be shared among the multiple satellites constituting the satellite constellation.

[0080] The above embodiment describes an example in which the registration procedure is performed via a low Earth orbit satellite, but it is not limited to this. For example, instead of a low Earth orbit satellite, the registration procedure may be performed via a medium Earth orbit satellite (MEO satellite) that orbits in a higher altitude than a low Earth orbit satellite, or via an aircraft such as a HAPS. In other words, the registration procedure may be performed by an aircraft that is closer to the ground than a geostationary satellite.

[0081] According to the embodiments described above, it is possible to reduce the power consumption related to wireless communication at NTN.

[0082] (Functional Configuration) Next, an example of the functional configuration of the base station 10C and terminal 20 that perform the processes and operations described above will be explained. The base station 10C and terminal 20 include functions to implement the embodiments described above. However, the base station 10C and terminal 20 may each have only some of the functions in the embodiments.

[0083] Figure 8 is a block diagram showing an example of the functional configuration of a base station according to the embodiment. As shown in Figure 8, the base station 10C has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. Note that the functional configuration shown in Figure 8 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operations according to the embodiment.

[0084] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The transmitting unit 110 also transmits inter-network node messages to other network nodes.

[0085] The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 and obtaining information from higher layers, for example, from the received signals. The transmitting unit 110 has the function of transmitting NR-PSS, NR-SSS, NR-PBCH, DL / UL control signals, etc. to the terminal 20. The receiving unit 120 also receives inter-network node messages from other network nodes.

[0086] The setting unit 130 stores pre-configured setting information and various setting information to be transmitted to the terminal 20. The content of the setting information includes, for example, the communication information described in this embodiment.

[0087] The control unit 140 performs control related to signal transmission and reception and control related to the use of the inference model, as described in the embodiment. The signal transmission function in the control unit 140 may be included in the transmission unit 110, and the signal reception function in the control unit 140 may be included in the reception unit 120.

[0088] Figure 9 is a block diagram showing an example of the functional configuration of a terminal in an embodiment. As shown in Figure 9, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. Note that the functional configuration shown in Figure 9 is merely an example. Any functional classification and functional unit names are acceptable as long as they can perform the operations according to the embodiment.

[0089] The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. Furthermore, for example, when performing D2D communication, the transmitting unit 210 may transmit PSCCH (Physical Sidelink Control Channel), PSSCH (Physical Sidelink Shared Channel), PSDCH (Physical Sidelink Discovery Channel), PSBCH (Physical Sidelink Broadcast Channel), etc., to other terminals 20.

[0090] The receiving unit 220 wirelessly receives various signals and acquires signals from higher layers based on the received physical layer signals. The receiving unit 220 also has the function of receiving NR-PSS, NR-SSS, NR-PBCH, DL / UL / SL control signals, etc. transmitted from the base station 10C. When performing D2D communication, the receiving unit 120 may also receive PSCCH, PSSCH, PSDCH, or PSBCH, etc. from other terminals 20.

[0091] The setting unit 230 stores various setting information received from the base station 10C by the receiving unit 220 in memory and reads it from memory as needed. The setting unit 230 also stores pre-set setting information. The content of the setting information is, for example, the communication information described in this embodiment.

[0092] The control unit 240 controls the entire terminal 20, including control related to signal transmission and reception. Alternatively, the signal transmission function of the control unit 240 may be included in the transmission unit 210, and the signal reception function of the control unit 240 may be included in the reception unit 220.

[0093] Terminal 20 may report the following capabilities to base station 10C: the capabilities of each operation described above, the capabilities of each option of an operation, or the capabilities of a combination of options, or the capabilities of each alternative in an operation, or the capabilities of a combination of alternatives.

[0094] Terminal 20 can report the above capabilities for each frequency. For example, the above capabilities may be reported for each terminal 20, for each FR (Frequency Range) 1, FR2, FR2-1, FR2-2, for each SCS (Subcarrier Spacing), for each band or bandwidth, for each BC (Band Combination), for each FS (Feature Set), or for each FSPC (Feature Set Per Component-carrier).

[0095] Terminal 20 can report the above capabilities for each cell. For example, the above capabilities may be reported for each terminal 20, each cell, or for each TDD (Time Division Duplex) and FDD (Frequency Division Duplex).

[0096] Throughout the above operations, whether or not they apply, which operations apply, or which options or alternatives are used may be determined, for example, by at least one of the following (a) through (g): (a) set by higher-layer parameters; (b) determined by relevant higher-layer parameters; (c) notified by MAC-CE (Media Access Control Control Element) or DCI (Downlink Control Information); (d) determined based on terminal 20 capabilities; (e) described in the operations described above; (f) determined based on the conditions described in the operations described above; (g) determined by the settings of higher-layer parameters / MAC-CE / DCI and reported terminal 20 capabilities.

[0097] Throughout the entire process, multiple options and alternatives can be combined into a single option or alternative.

[0098] According to the embodiments described above, in the terminal 20, the control unit 240 may select the first cell C1 of the first base station 10C-1 that provides wireless communication via the geostationary satellite 10A-1, and the second cell C2 of the second base station 10C-2 that provides wireless communication via the low Earth orbit satellite 10A-2. The transmission unit 210 may transmit a message regarding the registration request to the second cell C2.

[0099] Furthermore, in terminal 20, the receiving unit 220 may receive a message from the second cell C2 regarding the acceptance of the registration request. When the receiving unit 220 receives a message regarding the acceptance of the registration request, the control unit 240 may set the receiving unit 220 to receive a paging message from the first cell C1 and stop the cell search for the second cell C2.

[0100] Furthermore, in terminal 20, the receiving unit 220 may receive paging messages transmitted from the first cell C1. The transmitting unit 210 may send a message relating to a service request to the second cell C2.

[0101] Furthermore, in the second base station 10C-2, the control unit 140 may manage the wireless connection and context related to the terminal 20. When the transmitting unit 110 releases the wireless connection and context related to the terminal 20, it may send a message to the AMF310 that includes information designating the first base station 10C-1, which provides wireless communication via geostationary satellite 10A-1, as the destination for the paging message.

[0102] Furthermore, at the second base station 10C-2, the receiving unit 120 may receive paging messages from network nodes. The transmitting unit 110 may transmit paging messages to the first base station 10C-1, which provides wireless communication via the geostationary satellite 10A-1.

[0103] (Hardware configuration) The block diagram used in the description of the above embodiment shows functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are accessed directly or indirectly (for example, using wired or wireless connections) and these multiple devices are accessed. A functional block may be realized by combining the one or multiple devices with software.

[0104] For example, the base station 10C, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 10 is a diagram showing an example of the hardware configuration of the base station 10C and terminal 20 according to one embodiment of the present disclosure. The base station 10C and terminal 20 described above may be physically configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, bus 1007, etc.

[0105] In the following explanation, the term "device" can be interpreted as a circuit, device, unit, module, chip, etc. The hardware configuration of the base station 10C and terminal 20 may include one or more of the devices shown in the figure, or it may be configured to omit some of the devices.

[0106] Each function in the base station 10C and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, which allows the processor 1001 to perform calculations and control communication by the communication device 1004, or control at least one of reading and writing data to the memory 1002 and storage 1003.

[0107] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the control unit 140, control unit 240, etc., described above may be implemented by the processor 1001.

[0108] Furthermore, the processor 1001 reads programs (program code), software modules, or data from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 140 of the base station 10C may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and other functional blocks may be implemented similarly. Also, for example, the control unit 240 of the terminal 20 may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and other functional blocks may be implemented similarly. The above-described processes have been explained as being executed by one processor 1001, but they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may be transmitted from the network via a telecommunications line.

[0109] Memory 1002 is a computer-readable recording medium and may consist of at least one of the following: ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM) (registered trademark), RAM (Random Access Memory), etc. Memory 1002 may also be called a register, cache, main memory, etc. Memory 1002 can store executable programs (program code), software modules, etc., for implementing a communication method according to one embodiment of this disclosure.

[0110] The storage 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disc, a digital multipurpose disc, a Blu-ray® disc), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. The storage 1003 may also be called an auxiliary storage device. The above-mentioned storage medium may be, for example, a database, server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0111] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may include a high-frequency switch, duplexer, filter, frequency synthesizer, etc. For example, the transmitting / receiving antenna, amplifier section, transmitting / receiving section, transmission path interface, etc., may be implemented by the communication device 1004. The transmitting / receiving section may be implemented in a physically or logically separated manner, consisting of a transmitting section and a receiving section.

[0112] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0113] Furthermore, each device, such as the processor 1001 and the memory 1002, is accessed by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0114] Furthermore, the base station 10C and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array), and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0115] (Supplement to the embodiment) While one embodiment of the present disclosure has been described above, the disclosed invention is not limited to such an embodiment, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Where specific numerical examples are used to facilitate understanding of the present disclosure, unless otherwise specified, these numbers are merely examples, and any appropriate values ​​may be used. Where items are separated in the above description, the separation of items is not essential, and matters described in two or more items may be used in combination as necessary, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in a functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. The processing procedures described in the embodiments may be rearranged as long as they do not contradict each other. For the convenience of explaining the processing, the base station 10C and terminal 20 have been described using a functional block diagram, but such devices may be implemented in hardware, software, or a combination thereof. The software operated by the processor of the base station 10C according to the embodiment and the software operated by the processor of the terminal 20 according to the embodiment may be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, registers, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

[0116] Each aspect / embodiment described in this disclosure is LTE (Long Term Evolution), LTE-A (LTE-Advanced), IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 5G-A (5G-Advanced), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (where x is, for example, an integer or decimal)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), Open RAN (Open Radio Access Network), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE This standard may apply to at least one of the following: 802.11, IEEE 802.11x (where x is any string such as b, a, g, n, ac, ax, be, bn, etc., and x=n is also referred to as Wi-Fi 4, x=ac as Wi-Fi 5, x=ax as Wi-Fi 6 or Wi-Fi 6E, x=be as Wi-Fi 7, x=bn as Wi-Fi 8, etc. Wi-Fi is a registered trademark), IEEE 802.16 (WiMAX®), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth®, and other appropriate systems, as well as next-generation systems that are extended, modified, created, or defined based on these standards. Multiple systems may also be applied in combination.

[0117] In this disclosure, terms such as "Base Station (BS)", "Radio Base Station", "Fixed Station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "Access Point (AP)", "Transmission Point (TP)", "Reception Point (RP)", "Transmission / Reception Point (TRP)", "Radio Unit (RU)", "Remote Unit (RU)", "Control Unit (CU)", "Distributed Unit (DU)", "Remote Radio Head (RRH)", "Node", "Gateway", "Ground Base Station", "Stratospheric Base Station", "Unmanned Aerial Vehicle", "High Altitude Platform Station (HAPS)", and "Airborne Platform" may be used interchangeably. Each cell contained within a base station may also be referred to by terms such as macrocell, small cell, femtocell, picocell, serving cell, and supercell. Each cell may also be referred to as a "sector," "cell group," "carrier," "component carrier," "cluster," "bandwidth part (BWP)," or "carrier bandwidth."

[0118] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform information-based control or operation.

[0119] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0120] A terminal may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, router (e.g., home router, mobile router, etc.), TCU (Telematics Control Unit), or several other appropriate terms.

[0121] A base station and a terminal may each consist of one or more devices. Devices constituting at least a part of each base station and terminal may be called transmitting devices, receiving devices, communication devices, etc. Devices constituting at least a part of each base station and terminal may be, for example, the objects themselves, such as vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, unmanned aerial vehicles, stratospheric base stations (e.g., High Altitude Platform Stations (HAPS)), artificial satellites (e.g., Low Earth Orbit (LEO) satellites, Middle Earth Orbit (MEO) satellites, Geostationary Earth Orbit (GEO) satellites), drones (registered trademark), multicopters, quadcopters, balloons, smart meters, sensors, and other IoT (Internet of Things) devices, or include, but are not limited to, objects or devices mounted on such objects. Furthermore, the object in question may be a moving object (hereinafter referred to as a "moving object"; this does not exclude the possibility of the moving object being in a stationary state) or a fixedly positioned object (hereinafter referred to as a "non-moving object").

[0122] Furthermore, the term "base station" in this disclosure may be interpreted as "terminal." For example, the various aspects / embodiments of this disclosure may be applied to configurations in which communication between a base station and a terminal is replaced with communication between multiple terminals (which may be called, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.) or communication over a non-terrestrial network (NTN). In this case, the terminal 20 may have at least some of the functions of the base station 10C described above. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "sidelink") or terms corresponding to NTN (for example, "feeder link"). For example, uplink channel or downlink channel may be interpreted as sidelink channel.

[0123] Furthermore, this disclosure is also applicable when at least some of the equipment constituting the base station and terminal operates outside of the ground (for example, in the atmosphere or in outer space).

[0124] Furthermore, the term "terminal" in this disclosure may be interpreted as "base station." In this case, the base station 10C may have the same functions as the terminal 20 described above.

[0125] Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other methods. For example, notification of information may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), higher layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling), broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals, or combinations thereof. RRC signaling may also be referred to as an RRC message or an Information Element within such RRC message. The RRC message may be used for purposes such as controlling an RRC connection (e.g., setup, reconfiguration, establishment, reestablishment, release, or resume), mobility, measurement reporting, or notification of terminal capability, or it may be an information element within the message. The notification of information may be explicit or implicit. An explicit notification of information means notifying the information itself, while an implicit notification of information may be the notification of information other than the information in question, or the information may be considered notified due to the fulfillment of certain conditions. Furthermore, the notification of information may include not only notifications between the same layer of different devices (e.g., between lower layers or upper layers of base station 10C and terminal 20), but also notifications between different layers within the same or different devices (e.g., between lower and upper layers within base station 10C or terminal 20). Furthermore, the notification of information from one device to another may be carried out via one or more devices.

[0126] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described in this disclosure may be reordered, provided they are consistent with each other. For example, the methods described in this disclosure present various step elements using exemplary order and are not limited to the specific order presented.

[0127] The specific operations described in this disclosure as being performed by a base station may, in some cases, be performed by its upper node, or by a part of it (e.g., CU, RU, or DU). It is clear that various operations performed for communication with terminals in the RAN or CN may be performed by at least a part of the base station and other network nodes other than the base station. Although the above example illustrates the case where there is one other network node other than the base station, there may be a combination of multiple other network nodes. Network nodes are, for example, nodes located in various core networks such as EPC and 5GC, but are not limited to these.

[0128] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way.

[0129] Radio resources can be defined by a combination of units of resources in one or more domains, such as the time domain, frequency domain, spatial domain, code domain, and power domain.

[0130] For example, resources in the time domain may be defined by one or more time units. Such one or more time units include, but are not limited to, at least one of the following: radio frame, subframe, slot, symbol, and transmission time interval (TTI). Furthermore, such time units may be fixed-length time units that do not depend on numerology, variable-length time units that depend on numerology, or both. Examples of fixed-length time units include, but are not limited to, subframes consisting of one or more slots, and radio frames containing multiple subframes. Examples of variable-length time units include, but are not limited to, symbols and slots containing a fixed number of symbols. Note that a certain time unit may be divided into shorter time units. Examples of shorter time units include, but are not limited to, mini-slots consisting of fewer symbols than the number of symbols that make up a slot. The time units described above may include, for example, time units used as units for scheduling, link adaptation, and the like.

[0131] Numerology refers to parameters that define the physical layer structure, and may be based on, for example, at least one of the subcarrier spacing (SCS), symbol length, cyclic prefix length, and sampling time.

[0132] Resources in the frequency domain may be defined, for example, by one or more frequency units. Such one or more frequency units may include, for example, at least one of the following: a subcarrier, a resource block (RB), a bandwidth part (BWP), or a carrier bandwidth, but the names of the frequency units are not limited to these. Furthermore, the number of subcarriers included in a frequency unit may be a fixed number regardless of the neurology, or it may be a variable number that changes according to the neurology. For example, an RB may consist of a predetermined number of consecutive subcarriers in the frequency domain, and the number of subcarriers included in the RB may be the same regardless of the neurology, for example, 12, but is not limited to this. Similarly, a BWP may consist of, for example, one or more consecutive RBs within a certain carrier bandwidth, but is not limited to this. For terminal 20, one or more BWPs may be set within one carrier, and at least one of the BWPs may be activated.

[0133] Furthermore, resources in both the time domain and the frequency domain may be defined, for example, by one or more time / frequency units composed of time units and frequency units. Such time / frequency units are, but are not limited to, a resource element (RE) consisting of one symbol and one subcarrier, a resource element group (REG) consisting of a predetermined number of REs, or a control resource set (CORESET) consisting of a predetermined number of symbols and a predetermined number of RBs.

[0134] Furthermore, resources in the spatial domain may be defined by, for example, one or more spatial resources. Such spatial resources may be, but are not limited to, beams, MIMO (Multiple Input Multiple Output) layers, antenna ports, etc.

[0135] Furthermore, resources in the code domain may be defined by, for example, one or more code resources. Such code resources may be, but are not limited to, cyclic shifts (CS) or orthogonal spread codes (OCC).

[0136] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0137] In the above-described configuration of each device, the term "part" may be replaced with "means," "circuit," "device," etc.

[0138] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). A signal may also be a message.

[0139] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0140] Each aspect / embodiment described herein may be used individually, in combination, or switched between as needed during execution.

[0141] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way.

[0142] (Note) The following is added regarding one embodiment of this disclosure. [Note 1] A control unit (step S104) that selects a first cell of a first base station that provides wireless communication via a geostationary satellite and a second cell of a second base station that provides the wireless communication via an aircraft that is closer to the ground than the geostationary satellite, A transmission unit (step S107) that sends a message (RRCSetupComplete message) regarding a registration request to the second cell. A terminal equipped with the following. [Note 2] The system further comprises a receiving unit (step S108) that receives a message (DLInformationTransfer message) regarding registration acceptance in response to the registration request from the second cell, When the control unit receives a message regarding registration acceptance, it sets the receiving unit to receive a paging message from the first cell and stops the cell search for the second cell (step S108). The terminals listed in Appendix 1. [Note 3] A receiving unit that receives the paging message sent from the first cell (steps S207, S308) It further comprises, The transmitting unit sends a message (RRCSetupComplete message) relating to a service request (SERVICE REQUEST) to the second cell (step S403). The terminals listed in Appendix 1. [Note 4] A control unit that manages the wireless connection and context related to the terminal, When releasing the wireless connection and context related to the terminal (step S201), the transmitting unit (step S205) sends a message (UE CONTEXT RELEASE COMPLETE message) to the network node (AMF310) that includes information (Information on Recommended Cells and RAN Nodes for Paging) specifying the base station (first base station 10C-1) that provides wireless communication via geostationary satellite as the destination for the paging message. A base station (second base station 10C-2) equipped with the following. [Note 5] A receiving unit (step S305) that receives paging messages from network nodes, A transmitting unit (step S307) transmits the aforementioned paging message to a base station (first base station 10C-1) that provides wireless communication via a geostationary satellite. A base station (second base station 10C-2) equipped with the following. [Note 6] The device, Selecting a first cell of a first base station that provides wireless communication via a geostationary satellite, and a second cell of a second base station that provides the wireless communication via an aircraft closer to the ground than the geostationary satellite, Sending a message regarding the registration request to the second cell A communication method that includes the following. [Explanation of symbols]

[0143] 10 RAN 10A flying object 10A-1 Geostationary orbit satellite 10A-2 Low Earth Orbit Satellite 10B Ground station 10B-1 First Ground Station 10B-2 Second Ground Station 10C base station 10C-1 First base station 10C-2 Second base station 20 devices 30 Core Network 110,210 Transmitter 120,220 Receiver 130,230 Setting section 140,240 Control Unit 1001 Processor 1002 memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus C1, the first cell C2, the second cell FL Feeder Link SA1, SA2, SA3 Service Area SL Service Link

Claims

1. A control unit that selects a first cell of a first base station that provides wireless communication via a geostationary satellite, and a second cell of a second base station that provides the wireless communication via an aircraft that is closer to the ground than the geostationary satellite, A transmission unit that sends a message regarding the registration request to the second cell. A terminal equipped with the following.

2. The system further comprises a receiving unit that receives a message regarding the acceptance of the registration request from the second cell, When the receiving unit receives a message related to registration acceptance, the control unit sets the receiving unit to receive a paging message from the first cell and stops the cell search for the second cell. The terminal according to claim 1.

3. A receiving unit that receives the paging message transmitted from the first cell. It further comprises, The transmitting unit transmits a message relating to the service request to the second cell. The terminal according to claim 1.

4. A control unit that manages the wireless connection and context related to the terminal, When releasing the wireless connection and context related to the terminal, the transmitting unit sends a message to the network node containing information that designates a base station providing wireless communication via geostationary satellites as the destination for the paging message. A base station equipped with the following features.

5. A receiving unit that receives paging messages from network nodes, A transmitting unit that transmits the paging message to a base station that provides wireless communication via a geostationary satellite. A base station equipped with the following features.

6. The device, Selecting a first cell of a first base station that provides wireless communication via a geostationary satellite, and a second cell of a second base station that provides the wireless communication via an aircraft closer to the ground than the geostationary satellite, Sending a message regarding the registration request to the second cell A communication method that includes the following.

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